Gesundheitliche Auswirkungen von künstlichem Licht

7. Are there potential health risks linked to artificial lights?

The SCENIHR opinion states:

4. OPINION

This opinion is based on a scientific rationale which has
taken into account the relevant scientific literature and other
accessible and reliable information on physical and technical
characteristics of lighting technologies, principles of optical
radiation, as well as biological and health effects of optical
radiation. Health effects due to optical radiation have been
considered both for the general population and for persons with
photosensitive or other pathological conditions. Since the
assignment also includes evaluation of possible health effects
of various types of lighting technologies, additional data
regarding lamp emissions was requested and some were obtained
from stakeholders. In addition, for assessment purposes, data
regarding exposure patterns was sought, but found to be virually
lacking. This lack of information has seriously hampered efforts
to perform specific risk assessments.

We have received some information regarding emission data,
which has been used for our evaluation, for more than 180
different lamps. These lamps represent all major lamp types that
are used for general lighting purposes (tubular
fluorescent lamps;
compact fluorescent
lamps (CFLs) with and without a second envelope; halogen
lamps that are either high or low voltage; high pressure
discharge lamps (metal halide and sodium); light emitting diodes
(LEDs); and incandescent
lamps, although the degree of representativeness is
uncertain. Regarding specific lamp types, CFLs are well
represented in this collection, whereas LEDs for example have
been measured in only a few cases. Based on the lamp emissions,
the Standard EN 62471 (and also IEC 62471 and CIE S009, since
they are all identical in this sense) categorizes the lamps
according to the photo-biological hazard that they might pose.
The different hazards are:

Actinic UV-hazard for eye and skin.

UVA-hazard for the eye.

Blue-light hazard for the retina.

Thermal retina hazard.

IR-hazard for the eye.

Following the standards, emission measurements should be
performed according to two approaches; namely at a distance
where a light intensity of 500 lx is obtained and also at a
distance of 20 cm. Based on these measurements, lamps are then
classified according to the “Risk Group” (RG) to which they
belong. RG0 (exempt from risk) and RG1 (minor risk) do not pose
any hazards during normal circumstances. RG2 (medium risk) lamps
also do not normally pose any hazards, due to our aversion
responses to very bright light sources or due to the fact that
we would experience thermal discomfort. RG3 (high risk) include
only lamps where a short-term exposure poses a hazard.
Importantly, this classification is based on acute exposure
responses (a single day, up to 8 hours) and applies only to
individuals of normal sensitivity. It should be noted, with
respect to RG3 that the risk classification does not consider
either long-term exposures or particularly sensitive persons in
the population.

SCENIHR’s answers to the questions given in the Terms of
Reference are given directly in connection with the questions
below:

A: To explore and report scientific evidence on potential
health impacts on the general public caused by artificial
light of which the main purpose is to radiate in the visible
range (as opposed to artificial light where the invisible
part of the radiation is the main purpose, e.g. suntanning
lamps or infrared
lamps). The impacts of the light from all available
electrical lighting technologies should be studied, both in
the visible and invisible range (with specific analyses of
the ultraviolet
radiation subtypes UVA, UVB and UVC).

A combined assessment of natural and artificial light shows
that adverse health effects due to optical radiation can either
occur acutely at certain levels of exposure, or after long-term
repeated exposures at lower levels. Depending on the effect
(endpoint) of concern (e.g. skin burn,
skin cancer, retinal
damage, cataract) either
the intensity or duration of exposure is of most relevance. In
general, the probability that artificial lighting for visibility
purposes induces any acute pathologic conditions is low, since
expected exposures are much lower than the levels where effects
are known to occur in healthy people and are also much lower
than in typical summer daylight. The available lamp emission
data show that for all investigated hazard outcomes, the
absolute majority of lamps are classified as Risk Group 0 (RG0;
"exempt from risk"). Most of the rare exceptions are classified
as Risk Group 1 (RG1; "low risk"). The very few lamps assigned
to higher Risk Groups were either measured without the required
UV-shielding glass cover, or at a very short distance (20 cm)
which is not the intended use distance for this lamp
type.

Standard EN 62471 gives limits that are protective against
acute effects, while long-term effects are only marginally
considered. Thus the emissions in e.g. the UV range may comply
with these limits, but may still have an effect on skin
carcinoma incidences when a population is subjected to extensive
and large scale exposure to these lamps. A common exposure
situation, such as most household lighting, would involve an
illumination level which is so low that exposure to potentially
problematic radiation is considered negligible (with the
possible exception of prolonged task lighting with a lamp close
to the body which may lead to UV exposures approaching the
current workplace limit set to protect workers from skin and
retinal damage). However, according to a worst case scenario
developed in the scientific rationale, the highest measured
emissions of UV from fluorescent
lamps used typically indoors in professional
environments, although well below the limits for RG0, could be
contributing to the number of squamous cell carcinomas in the EU
population. This is in comparison to a hypothetical situation
where the same population is not exposed to UV radiation from
artificial light indoors. The annual erythemal UV dose expected
from the worst case scenario approximately corresponds to the
dose one would get from a half week Mediterranean holiday.
Fluorescent lamps typically emit less than half of the UV
radiation assumed in the worst case scenario. The vast majority
of the CFLs tested emit erythemal UV at very low levels,
amounting at the most to an extra day of sunbathing a year.

Low levels of UV emissions may occur from certain lamp types
(quartz halogen lamps, single- and double-capped
fluorescent lamps
as well as incandescent light
bulbs). These emissions may, in some cases, in
particular for certain halogen lamps with poor UV filtering,
include UVC in addition to UVA and UVB. UVC is not naturally
present on Earth due to the blocking action of the earth’s
atmosphere, so any emissions from lamps would provide a novel
type of exposure. However, most action spectra on skin and eye
effects include UVC. Hence, biologically effective doses take
UVC into account and are thus considered in the categorization
of the Risk Group, as discussed above. However, detectable
levels of UVC do signal a considerable overall output of
biologically harmful short wavelength UV radiation. Regarding a
possible need for separate UVA, UVB or UVC radiation limits for
tungsten halogen lamps and other light sources that emit UV
radiation, the Scientific Committee considers that there is no
scientific basis for making such specific recommendations beyond
the established dose limits.

Evidence from in vitro experiments suggests that blue light at
10 W/m2 induces
photochemical retinal
damage (Class II) upon acute (hours) exposure, and animal
experiments and in vitro studies suggest that cumulative blue
light exposure below the levels causing acute effects also can
induce photochemical retinal damage. There is no consistent
evidence from epidemiological studies regarding the effect of
long-term exposure to sunlight (specifically the blue component
of sunlight) on photochemical damage to the
retina (particularly to
the retinal pigment epithelium), which may contribute to
age-related macular degeneration (AMD) later in life. Whether
exposure from artificial light could have effects related to AMD
is uncertain. There is no evidence that artificial light from
lamps belonging to RG0 or RG1 would cause any acute damage to
the human eye. Studies dedicated to investigating whether
retinal lesions can be induced by artificial light during normal
lighting conditions are not available. Lamp types belonging to
RG2 and higher are usually meant to be installed by
professionals in locations where they do not pose a risk.
Chronic exposure to
blue light from improperly used lamps could, in theory, induce
photochemical retinal damage. There is however no evidence that
this constitutes a risk in practice. It is unlikely that chronic
exposures to artificial light during normal lighting conditions
could induce damage to the
cornea,
conjunctiva or
lens. Besides the
beneficial effect of light, e.g. through synchronising the
day-night rhythm, there is mounting evidence suggesting that
exposure to light at night while awake (especially during
shiftwork), may be associated with an increased risk of breast
cancer and also
cause sleep, gastrointestinal, mood and
cardiovascular
disorders possibly through circadian rhythm disruption.
Importantly, these effects are associated with light, without
any specific correlation to a given lighting technology.

B: To update the SCENIHR report on Light Sensitivity (from
23 September 2008) in light of further evidence, and to
examine the aggravation of the symptoms of pathological
conditions in the presence of lamp technologies other than
compact fluorescent
lamps (including conventional incandescent and
halogen lamps, halogen lamps with improved efficiency and
light emitting diode lamps).

The previous SCENIHR opinion on Light Sensitivity (SCENIHR
2008) identified that some pre-existing conditions
(epilepsy,
migraine, retinal
diseases, chronic actinic
dermatitis, and solar
urticaria) could be exacerbated by flicker and/or
UV/blue light. However, at that time there was no reliable
evidence that compact fluorescent
lamps (CFLs) could be a significant contributor. This
conclusion needs updating as more recent studies indicate a
negative role for certain CFLs and other artificial light
sources (including sometimes incandescent bulbs) in
photosensitive disease activity. There are no published data on
the effect of exposure of a photosensitive patient to light from
halogen lamps.

There is strong evidence that UV and, in some patients
visible light, can
induce skin lesions of true photodermatoses. Although sunlight
is reported by most patients as the main trigger of disease
activity, occasionally severely affected patients over the range
of endogenous (and exogenous) diseases report a provocative role
for artificial lighting. There is a lack of controlled skin
provocation studies relating effects to the magnitude and the
wavelength components of the light source, although there is
evidence that the shorter wavelength light components (blue or
UV) tend to be more effective than the longer wavelength
components (red) in aggravating pre-existing conditions. Some
research work has been conducted in particularly severely
affected individuals suffering from photodermatoses such as
lupus
erythematosus, chronic
actinic dermatitis and
solar urticaria. This
provides good evidence for the aggravation of symptoms related
to these pre-existing skin diseases. Such work needs to be
confirmed, and also extended using a range of lamp types over a
wider range of diseases in greater numbers of patients.
Particular attention seems justified for the individual
variability of the conditions for aggravation of such diseases.
Until such data exist, it seems reasonable to assume that the
UV, and in some cases the blue radiation component of artificial
lighting in an as yet undefined number of patients, may
contribute to the aggravation of symptoms related to their skin
disease, and in the case of lupus erythematosus possibly also to
the aggravation of their systemic disease.

Generally, double envelope CFLs emit much less UV radiation
than single envelope CFLs. Most LEDs in general use emit little
or no UV radiation. However, with the considerable variability
of UV/blue light components for lighting technologies, even of
the same or similar kind, no general advice can be given and
individual optimisation of the lighting technology is advised
for these patients.

The effect of light is variable depending on the genetic
alterations that are causing inherited retinal degeneration. In
specific conditions like Stargart disease, the retinal pigment
epithelial (RPE) cells are
particularly sensitive to Class II
photochemical damage,
which is induced by peaks at shorter wavelengths. In other
retinal dystrophies, light does not exert any aggravating
effect. However, since the causative mutation is seldom known to
the patient or their family, and because there is no clear
correlation between genotype and phenotype, it is recommended
for all patients with retinal dystrophy to be protected from
light by wearing special protective eyeware that filter the
shorter and intermediate wavelengths.

The previous SCENIHR opinion on Light Sensitivity stated that
modern CFLs are basically flicker-free due to their electronic
high frequency ballasts. However, it was also noted that studies
indicated that residual flicker can occur during certain
conditions, at times also related to other circuitry like
dimmers operated with the light source, in both CFLs and
incandescent bulbs. In principle, there can be a residual
sinusoidal modulation of the light of any light source at twice
the line frequency of e.g. 50-60 cycles. Any light source
operated on DC, after transformation from the AC line, is
flicker-free. This has been the predominant case for LED
operation, but is also applicable to other lighting
technologies, e.g. halogen and
incandescent lamps.
Flicker cannot typically be observed in static settings above
about 60-80 cycles, while in conjunction with dynamic scenes,
the effect is still visible at higher frequencies. There is no
scientific evidence available to evaluate if conditions such as
Irlen-Meares syndrome, myalgic encephalomyelitis,
fibromyalgia,
dyspraxia, autism,
and HIV infection are influenced by the lighting technologies
considered in this opinion.

C: If health risks are identified under points A or B, to
estimate the number of EU citizens who might be at risk and
identify the level of emission/exposure safeguarding the
health of citizens and/or means to mitigate or entirely
prevent the impact of the problematic parameter of the light
technology in question.

All healthy individuals may be at some risk from UV radiation
and blue light from indoor lighting, albeit to different degrees
due to differences in genetic background and in the type of
light source used. Short-term UV effects on healthy people are
thought to be negligible. A proper assessment of long-term risks
due to daily low level UV exposure is not possible because data
on actual personal indoor UV exposure are lacking. Due to this
knowledge deficit, it would appear advisable to be cautious and
to develop worst case scenarios. The worst case scenario
examined in this opinion involved workplace/school exposure to
double- or single-capped
fluorescent lamps in
ceiling-mounted open luminaires. This scenario assumes the
validity of extrapolating from studies on animals with short
lifespans to life-time human exposures. Furthermore, it assumes
the appropriateness of dose-level extrapolation from
experimental studies to real human exposures and that all
individuals in a population experience the same risk independent
of susceptibility factors. If we take lamps with the highest
measured UV output (still well within Risk Group 0), such
exposure adds the equivalent of 3 to 5 days vacation in a sunny
location to the average annual UV dose. Although this would lead
to an increase in the personal risk of
squamous cell
carcinoma, such an increase would remain small (a few %
over a lifetime in Denmark). Population-wide exposure to such
lamps could, however, add approximately 100 cases of squamous
cell carcinomas a year to a base line of 900 cases/year in
Denmark. It should be stressed that the UV output of most of the
fluorescent lamps tested fall well below this level, and are not
expected to affect squamous cell carcinoma incidences. Improper
use of lamps belonging to Risk Groups 1- 3 (due to missing or disregarded user information, non-professional installation) could cause retinal damage. While no such cases are known, appropriate measures could be considered to ensure that these lamps are not misused.

The current standardization of lighting lamps and luminaires in four risk categories appears sufficient to limit the personal short-term risk. However, RG0, as it is based on acute effects, should not be taken to imply adequate protection of the general population as a whole from effects after long-term exposure to UV radiation. Nevertheless, it would be useful to communicate information on risk categories to the consumer.

The previous SCENIHR opinion (SCENIHR 2008) stated that a number of patients are exceptionally sensitive to UV/blue light exposure. The number of EU citizens with light- associated skin disorders that would be affected by exposures from CFLs was estimated in the report to be around 250,000. Clearly, the risk for this group of patients is not limited to CFL, but includes all light sources with significant UV/blue light emissions. The lack of proper data precludes any improvement of the estimate of the size of the affected group.

Also photosensitivite patients undergoing photodynamic therapy
might be expected to react to CFL and LED sources to a greater
extent than to incandescent lighting. This is due to a
combination of greater sensitivity of porphyrins to blue light
(soret band), coupled with an enhanced blue light emission of
these sources. However, such patients are aware of their extreme photosensitivity which needs careful management.
For patients with light-associated skin disorders, the previous SCENIHR opinion recommended that, when using CFLs, a double envelope type is preferable. The current opinion supports that position. Double envelope CFLs generally emit much less UV radiation than single envelope CFLs and are much less likely to induce a reaction in patients with light-associated skin disorders. While a second envelope undoubtledly reduces the UV component of any particular lamp, the currently available data, however, documents the high variability of UV and blue light emissions due to different internal design parameters, even for the same externally visible architecture (i.e. also when a second envelope is present). While some compact fluorescent lamps are in the same category, retrofit LED
lighting, which does not emit UVR on the physical grounds of the
light generation therein, would potentially provide an even better option for such patients. However, for patients whose sensitivity extends into the visible part of the spectrum, it may be necessary to exclude LEDs which have a significant blue component. The UV/blue light irradiation from halogen lamps is also highly dependent on the lamp type. With lamps other than incandescent retrofit halogen bulbs, attention needs to be given to the proper installation, as they are at times sold by the manufacturer to be installed at larger distance or in conjunction with special luminaires or filters against e.g. UV or IR irradiation or to prevent other hazards like fires. While it is unlikely that there would be a significant UV risk from halogen lamps for the general public, provided that protective measures are complied with, the UV content can rise to levels which are of concern for patients with light-associated skin disorders at close operating distances and long exposure times, which is not a very common use pattern for this lamp type.

For individuals with photosensitive skin diseases a list of
lamp models (not only types) that are specifically suitable for
their situation is needed. The non-representative sample
spanning across a wide range of lighting technologies which is
provided by Schulmeister et al. (2011) provides a first try.
However, important issues like the modificationcurrently
assessed. In view of the large number of patients affected by photosensitive diseases it may be advisable to make sufficient information on the emitted spectrum for individual lamp models available to the healthcare professionals and their patients to allow them to choose their lighting solutions optimally.

D: To identify potential research needs related to the areas where the lack or scarcity of scientific evidence prevents SCENIHR from coming to firm conclusions.

The scientific rationale has identified a number of areas
where relevant data are lacking regarding the effects of
specific lighting technologies on medical conditions. The most
important areas where knowledge gaps have to be filled in order
to be able to draw firm conclusions related to this opinion
include:

Emission data (ranging from UVC up to 800 nm)
characterizing the different lighting technologies – a challenge
due to the variation of manufacturing parameters, and a database
of these characteristics of specific lamps on the European
market.

Exposure database on indoor visible light radiance to the
eye and personal UV exposures from various lamp types compared
to ambient outdoor exposure. The database should be established
in view of the potential conditioning of the eye due to the
largely different voluntary exposure to sunlight from one
individual to another, and for the also very different use
patterns for UV/ light protective eyewear between individuals
and populations.

Attention should be paid to develop a risk group
categorisation that takes into account potential chronic effects
like SCC.

The particular role of UVC components in artificial
lighting for skin diseases taking into account especially
sensitive populations and the role of prior exposure to
sunlight.

The effects of non-incandescent light sources, in
particular those with very inhomogenous or biased spectral
distribution on colour rendition, fatigue, and other components
of the human visual perception.

5. COMMENTS RECEIVED DURING THE PUBLIC CONSULTATION ON THE
HEALTH EFFECTS OF ARTIFICIAL LIGHT

A public consultation on this opinion was opened on the
website of the EU non-food scientific committees from 19 July to
30 September 2011. Information about the public consultation was
broadly communicated to national authorities, international
organisations and other stakeholders.

In total, 16 contributions were received of which four were
from public authorities, five from industry, one from academia,
two from NGOs and six from individuals and three others.

Most of the material submitted was relevant, contained
specific comments and referred to peer-reviewed scientific
literature. As a result, each submission was carefully
considered by the Working Group. Only three submissions from
industry disagreed with the preliminary opinion and the
submission from academia showed some disagreement. The document
has been revised to take account of the relevant comments and
the literature has been updated with relevant publications. The
scientific rationale was clarified and strengthened in certain
respects. The opinion, however, remained essentially unchanged.